The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
The development of xe2x80x9cmicro-satellitesxe2x80x9d has occasioned the use of multiple inexpensive orbiting satellite communication platforms. These communication platforms may be used by military, commercial, and amateur radio communicators for both digital and analog signal communications and usually involve communication over distances of five hundred to two thousand kilometers along a line of sight path inclusive of atmospheric and free space media. Older arrangements for communicating via such satellite platforms require substantial antenna gain for the uplink communication, the downlink communication, or both. This often means the operator needs to employ an elaborate ground antenna in order to use the satellite.
In recent years, radio amateurs have developed hand held antenna systems for use with low orbit satellites such as the satellites sponsored by many local chapters in their fraternity. Unfortunately, these antenna systems have often been characterized by a linear polarization characteristic and the operators have thereby experienced considerable fading in the communication these antennas support, fading as a result of the slow spin or tumble of the microsatellites and the antenna system incorporated therein. These fades in communication can however be minimized with the use of circularly polarized antenna systems. None of the thusly needed circularly polarized antenna systems are known however to have been developed in a package which is both strongly directional and sufficiently light to enable hand-held antenna disposition.
Another disadvantage of the available circularly polarized antennas lies in their assembled configuration. These antennas normally function in only one frequency band and must therefore be physically tied to a similarly directed antenna, using for example a cross linking boom, in order to support the second frequency band often used in a two-way satellite communication arrangement. In addition to being cumbersome during use, assembly or disassembly of such a combination of antennas is usually burdensome to an excessive degree. The antenna system of the present invention can however provide this multiple band communication in a form that may be assembled or disassembled in a few minutes. In disassembled form the present invention antenna system comprises a light and easily carried bundle. In assembled form the antenna system comprises a fully capable, directional, dual band antenna system, an antenna system of circular polarization in at least one of its operating bands and an antenna system especially suited to satellite communication but usable for other purposes, portable and fixed, as well. One such other purpose for an antenna system of this type is for example often employed in the amateur radio fraternity in connection with the xe2x80x9chidden transmitter huntxe2x80x9d events used to exercise direction-finding equipment; another purpose includes the direct ground to aircraft communication (without intervening satellite) used by special operation forces and others in present day military actions.
The present invention provides a handheld dual band satellite communication antenna system of partial or complete circular polarization characteristics.
It is therefore an object of the present invention to provide a lightweight relatively small dual band antenna system suited to satellite and other communication needs in the UHF and VHF bands of radio frequency.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be disassembled into an easily carried package.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be assembled from a carried package form to a functional antenna system form in a short time interval.
It is another object of the invention to provide a lightweight relatively small dual band antenna system having circular polarization characteristics in one or both of its operating bands.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be easily adapted to alternate operating frequencies.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be used for either signal transmission or reception functions on either of two operating frequency bands.
It is another object of the invention to provide a dual band antenna system that seizes upon the tuned trap element arrangement for achieving dual band antenna element operation.
It is another object of the invention to provide a lightweight relatively small dual band antenna system having favorable, significant gain-inclusive, field pattern characteristics in each of its operating frequency bands.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be fabricated from readily available, low cost, materials.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be fabricated from a variety of alternate materials of differing physical and structural characteristics.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be physically disposed in either hand held or fixed permanent mounting arrangements.
It is another object of the invention to provide a light-weight relatively small dual band antenna system that may be disposed in a variety of transmitter power level compatible configurations including an easily achieved 100 watt configuration.
It is another object of the invention to provide a light-weight relatively small dual band antenna system that is compatible with low earth orbit satellite apparatus having no more than ten watts of input energy.
It is another object of the invention to provide a lightweight relatively small dual band antenna system incorporating the advantages of the Yagi-Udi element arrangement.
It is another object of the invention to provide a lightweight relatively small dual band antenna system combining a single plane two-frequency linearly polarized antenna with a second plane antenna adding circular polarization characteristics.
It is another object of the invention to provide a lightweight relatively small dual band antenna system that may be easily and accurately reproduced.
It is another object of the invention to provide a lightweight relatively small dual band antenna system providing relatively low standing wave ratio electrical characteristics in each of its operating bands.
It is another object of the invention to provide a lightweight relatively small dual band antenna system having one embodiment that is suited to operation in the seventy centimeter and two meter wavelength operating bands.
These and other objects of the invention will become apparent as the description of the representative embodiments proceeds.
These and other objects of the invention are achieved by dual band circular polarization-capable portable antenna apparatus comprising the combination of:
an ultra high radio frequency first array of dipolar antenna elements disposed in a first geometric plane and extending along an antenna boom member in ultra high radio frequency Yagi/Uda element separations;
said ultra high radio frequency first array of dipolar antenna elements including an ultra high radio frequency energy radiator element disposed intermediate an ultra high radio frequency reflector element and a plurality of ultra high radio frequency director elements along said antenna boom member;
an ultra high radio frequency and very high radio frequency second array of dipolar antenna elements extending in ultra high radio frequency Yagi/Uda element separations along said antenna boom member within a second geometric plane orthogonal of and coaxial of said first geometric plane;
said ultra high radio frequency and very high radio frequency second array of dipolar antenna elements including an ultra high radio frequency energy radiator element disposed intermediate an ultra high radio frequency reflector element and a plurality of director elements, including dual radio frequency wavelength director elements of combined very high radio frequency and tuned wave-trap limited ultra high radio frequency effective electrical lengths, along said antenna boom member;
said dual radio frequency director elements of combined very high radio frequency and tuned wave-trap limited ultra high radio frequency effective electrical lengths additionally comprising a very high radio frequency-tuned antenna energy radiator element and a very high radio frequency-tuned antenna director element;
said ultra high radio frequency and very high radio frequency second array of dipolar antenna elements extending in said second geometric plane along said antenna boom member in interspersed antenna elements relationship with said first geometric plane first array of ultra high radio frequency dipolar antenna elements;
an electrical signal frequency responsive and signal phase splitting electrical network apparatus disposed intermediate an electrical port of said circularly polarized portable antenna apparatus and each of said antenna energy radiator elements;
said signal phase splitting electrical network of said electrical signal frequency responsive and signal phase splitting electrical network apparatus having output signal ports connecting with said ultra high radio frequency energy radiator elements of said first and second arrays of dipolar antenna elements in circular polarized wave generating element phasing determination.
By way of clarification and explanation, it may by now be appreciated, that to the best degree reasonably possible in drafting the present descriptive material, an attempt is made to use the expression xe2x80x9cantenna systemxe2x80x9d or xe2x80x9cantenna apparatusxe2x80x9d or similar terminology when referring to the overall FIG. 1 or FIG. 2 apparatus and to employ the word xe2x80x9cantennaxe2x80x9d or xe2x80x9cantenna elementxe2x80x9d or xe2x80x9celementxe2x80x9d when making generic reference to an antenna or reference to components or lesser assemblies or individual elements included within the complete apparatus.